A Low-Power Switched-Capacitor Capacitive Transducer With High Resolution

A new capacitive transducer using a pseudodifferential-input-single-ended output topology for low- power portable applications is presented. This is based on a switched-capacitor chopper-stabilized pseudodifferential integrator structure that is cascaded with a chopper-stabilized differential difference amplifier, consisting of a single output and a bandpass AC output. The measured results have shown that the transducer integrated circuit, with a sampling rate of 64 kHz in a 0.6-mum CMOS technology, dissipates 820 muA at a 3.3-V supply and exhibits a low noise characteristic. For a 100-Hz bandwidth, the input-referred minimum detectable capacitances are 57.24 and 33.82 aF with reference to the single output and the bandpass output, respectively.